1. Field of the Invention
The present invention relates to a method of encoding an image.
2. Description of the Related Art
A facsimile apparatus as a typical still image communication apparatus employs a method of encoding and transmitting an image based on MH or MR coding by sequentially scanning the image.
In this method, in order to recognize the entire image, all the image data must be transmitted, resulting in a long transmission time. It is difficult to apply this method to an image communication service, such as an image data base service, a videotex, or the like, in which an image must be quickly judged.
As an encoding method applicable to such a service, for example, a method, e.g., arithmetic coding, in which a pixel of interest is predicted on the basis of a plurality of surrounding pixels near the pixel of interest, and an image is encoded on the basis of coincidence/noncoincidence between the predicted pixel and an actual pixel of interest, is proposed.
With this method, encoding with higher efficiency can be achieved by a simpler arrangement than those for conventional MH or MR coding.
In such coding, however, parameters necessary for predicting a pixel of interest based on surrounding pixels are predetermined using a standard image. Therefore, for an image having a feature different from that of a standard image, a probability of prediction coming true is low, and coding efficiency is impaired. In some cases, encoded data may become longer than original data.